Terrestrial in situ cosmogenic nuclide production rate scaling models: Theory, progress, and prospects

High-energy cosmic rays bombard target atoms in near-surface minerals, initiating nuclear reactions that produce in situ cosmogenic nuclides such as ¹⁰Be and ²⁶Al. Advances in cosmogenic nuclide techniques have been enabled by well-understood production mechanisms, highly sensitive detection at ultra-trace levels, and robust quantitative that describe nuclide production, accumulation, transport, and decay in the near-surface environment. These techniques have advanced Earth science by providing tools for surface exposure dating, sediment burial dating, and quantifying denudation rates of watersheds and bedrocks. This article presents a comprehensive review of the research history of terrestrial in situ cosmogenic nuclide production rates, the theoretical frameworks and computational methodologies used to construct production rate scaling models, with particular attention to key controlling factors, and evaluates the differences among various production rate scaling models and their underlying causes. To improve the accuracy and precision of future production rate scaling models, we recommend the following four research priorities: (1) Enhance quantitative comparison and data assimilation between measured and simulated cosmic-ray spectra to refine particle-transport simulation algorithms and reduce uncertainties in secondary cosmic-ray energy spectra. (2) Reconstruct temporal variations in geomagnetic field intensity and solar activity since the Pleistocene to provide more robust constraints on time-dependent cosmic-ray energy spectra. (3) Systematically measure and theoretically evaluate proton- and neutron-induced cross sections on main target atoms (O, Si, Al, Fe, Mg, etc.) across energy ranges relevant to TCN production and compile the results into a comprehensive evaluated database. (4) Strengthen geological calibrations of production rates across multi-nuclide (³He, ¹⁰Be, ¹⁴C, ²¹Ne, ²⁶Al, ³⁶Cl, etc.) and multi-mineral (quartz, calcite, etc.) systems to develop a globally applicable, internally consistent production rate model.